[OSM-dev] Zeroing or Extending a Hillshade-Tiff

AJ Ashton aj.ashton at gmail.com
Wed Mar 13 16:26:47 UTC 2013

On Wed, Mar 13, 2013 at 12:13 PM, Jochen Topf <jochen at remote.org> wrote:

> On Tue, Mar 12, 2013 at 07:00:25PM +0100, Peter Körner wrote:
> > That's not that easy for the polar regions, because transforming the
> > splittet polygons to the destination projection results in gaps
> > because of straigt lines not beeing curved.
> >
> > For the land there are complete polygons which are used on the
> > Antarctica map but there are no complete water polygons, because
> > they would be too complex (a huge polygon with 400.000+ holes).
> >
> > So in order to get this right one would need to modify jochend
> > osmcoastline tool to support EPSG:3031 natively, to all corrdinates
> > are transformed before splitting and calculating the water polygons.
> Another option would be to split up the long straight lines resulting from
> the splitting into shorter pieces. If the pieces are short enough, it
> should
> be okay. Maybe there is some tool around that can do that easily? I don't
> want to put more and more of these things into OSMCoastline, because they
> are not really related to coastlines, but general issues with large
> objects.

I have done this in the past with the split land and water shapefiles to
work with polar projections. ogr2ogr's -segmentize option with a value of
0.1 worked well for me on the WGS84 files.

AJ Ashton
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